JPH0437576A - Recording medium - Google Patents

Abstract

PURPOSE:To enable the compatibility of a sufficient ink absorption and transparency(bottom haze) by providing a specific pseudo-boehmite in two layers. CONSTITUTION:A recording medium is provided with a pseudo-boehmite layer with the average pore size of 30-50Angstrom and with the volume of micropores having sizes within the range of + or -10Angstrom of the average micropore size concentrated upon 45% or more of the total micropore volume on a substrate. On the top of that layer, a lower layer provided with a pseudo-boehmite layer with the average micropore volume of 15-30Angstrom and with the volume of pores having a radius within the range of + or -10Angstrom of the average micropores concentrated upon 55% or more of the total pore capacity shows a high ink absorption and an upper layer contributes to the reduction of haze. In the pseudo-boehmite layer, the volume of micropores with the radius of 10-100Angstrom is preferably 0.5-1.0cc/g in the lower layer and 0.3-100cc/g in the upper layer. The thickness of the pseudo-boehmite layer is preferably 2-10mum in the lower layer and 2-15mum in the upper layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a recording medium, particularly a recording medium from which printed matter with transparency and low haze can be obtained.

[Prior art] In recent years, it has been used for presentations at various academic conferences and conferences.
Overhead projectors are increasingly being used in place of conventional slide projectors.Also, in the printing field, transparent printed matter is required for various publications and packaging applications.

Printing on these transparent sheets requires special consideration in terms of printing speed and drying compared to printing on ordinary paper because the base sheet itself has no absorbency. Opaque substrates often have poor absorbency and require similar considerations.

We also have sheets for overhead projectors (
In order to obtain small amounts of printed matter, it is widely used to edit manuscripts using a personal computer or word processor and then print them out using a printer, and inkjet printers are attracting attention because they can easily print in full color. .

[Problems to be Solved by the Invention] However, conventional recording media have sufficient ink absorbency and dry quickly, resulting in increased haze and loss of transparency. The good ones had insufficient ink absorption.

Particularly when this is an overhead projector, the effect is large, and the result is only blurred and cloudy images.

[Means for Solving the Problems] In order to solve these problems, the present inventor conducted various studies and examinations, and as a result, discovered that the object could be achieved by providing two layers of specific pseudo-boehmite.

Thus, the present invention provides a substrate with an average pore radius of 30-5.
Provide a pseudo-boehmite layer in which the volume of pores having a radius of 0 pores and a radius within the range of ±10 pores of the average pore radius is concentrated at 45% or more of the total pore volume, and further on top of the pseudo-boehmite layer, The average pore radius is 15 to 30, and ±1 of the average pore radius.
The volume of pores with a radius in the range of 0 is 5 of the total pore volume.
To provide a recording medium provided with a pseudo-boehmite layer having a concentration of 5% or more.

In the present invention, the pseudo-boehmite layer provided on the substrate needs to have the above-mentioned physical properties. If the above physical properties are exceeded, the absorption speed of the ink will be slow, blurring will occur in some areas, an unclear image will occur, and the outline of the image will become unclear, so it is not suitable. (Hereinafter, this pseudo-boehmite layer will be referred to as the lower layer.) Furthermore, it is necessary that the pseudo-boehmite layer provided thereon also have the above-mentioned physical properties. If the physical properties deviate from the above, the haze will not be sufficiently low (and the image will be clouded or a clear outline will not be obtained, making it unsuitable. Furthermore, this pseudo-boehmite has an average pore radius of 15 to 20 By using a material in which the volume of pores having a radius within the range of ±IO of the average pore radius is concentrated at 55% or more of the total pore volume, the occurrence of haze can be further suppressed. Preferably. (Hereinafter, this pseudo-boehmite layer will be referred to as an upper layer.) In the present invention, the lower layer exhibits high ink absorbency, and the upper layer contributes to reducing haze.

The pseudo-boehmite layer of the present invention has a lower layer of 10 to 10
It is preferable that the pore volume with a radius of 0 people is 0.5 to 1.0 cc/g, and in the upper layer, the pore volume with a radius of 10 to 100 people is 0.3 to 1.0 cc/g. It is preferable that it is Occ/g.

The thickness of the pseudo-boehmite layer is preferably 2 to 10 μm for the lower layer and 2 to 15 μm for the upper layer.

If the thickness of the lower layer is less than the above range, the absorbency will be poor and the image will become unclear due to bleeding etc. Conversely, if it exceeds the above range, the haze will be high and the image will become dark and unclear. Both are unfavorable.

If the thickness of the upper layer is less than the above range, the haze will be high (and the image will be dark and unclear), whereas if it exceeds the above range, the absorption will be poor, causing blurring and poor color density. Both are undesirable because the image becomes unclear.

The substrate used in the present invention is not particularly limited, and for example, organic films or sheets of polyethylene terephthalate, polyester, diacetate, etc. can be used. The thickness of these substrates is selected depending on the purpose and is not particularly limited. These substrates may be surface treated, such as corona discharge treatment, or provided with a precoat layer, if necessary, for the purpose of improving adhesion to the pseudo-boehmite provided thereon.

In fact, various methods can be used to provide pseudo-boehmite, or a mixed slurry of pseudo-boehmite and a binder may be prepared in advance and the slurry may be coated with a roll coater, air knife coater, blade coater, rod coater, etc.
A method of coating and drying using various coaters such as a bar coater is suitable.

Further, as the binder, in general, organic substances such as starch and modified products thereof, PVA and modified products thereof, SBR latex, NBR latex, hydroxycellulose, and polyvinylpyrrolidone can be used.

In this case, the ratio of pseudo-boehmite to binder is preferably 100+30 to 100:10 in solid weight ratio.

[Example] The recording sheets obtained in the Examples and Comparative Examples were evaluated by the following method.

(2) Printing: A pattern of 1 cm + w x 1 cm was printed in black using a Sharp color image jet printer 10-735.

■Color density: Back the sheet printed with ■ with white paper,
The reflected color density of black was measured using a Sakura densitometer PDA45.

■After resolution: Evaluation method in 4 stages based on bleeding and mixing of the pattern of the sheet printed in ■ (O: worst, 3: best) Example 1 6 parts of alumina silcataloid AS-3 (manufactured by Catalysts Kasei Co., Ltd.), Vinyl alcohol PVA117 (manufactured by Kuraray)
A coating solution with a solid content of 10% consisting of 2 parts (solid content) and water was prepared and coated on a polyethylene terephthalate film (OC type, thickness 100 μm, manufactured by Yojin Co., Ltd.) as a base material using a bar coater to a dry layer thickness of approximately It was coated to a thickness of 5 μm and dried. Furthermore, a coating liquid with a solid content of 9% consisting of 6 parts of alumina silcataloid AS-2 (manufactured by Catalysts Kasei Co., Ltd.), 1 part (solid content) of polyvinyl alcohol PVA117 (manufactured by Kuraray Co., Ltd.) and water was prepared on top of it, and dried. The coating was applied to a layer thickness of approximately 5 μm and dried to obtain a recording medium.

Example 2 A recording medium was obtained in the same manner as in Example 1, except that the dry layer thickness of the alumina silcataloid AS-3 provided on the base material was changed to about 2 μm.

Example 3 Alumina silcataloid AS- on a substrate according to Example 1
A transparent sol obtained by coating 3, drying, and hydrolyzing and dissolving aluminum isopropoxide 8 parts (solid content) polyvinyl alcohol PVA117 (manufactured by Kuraray Co., Ltd.)
A recording medium was obtained in the same manner as in Example 1, except that a coating liquid having a solids content of about 9% and consisting of 1 part (solid content) and water was prepared. The layer thickness was approximately 5 μm for both the upper and lower layers.

Comparative Example 1 The alumina sol provided on the base material in Example 1 was AS-
A recording medium was obtained in the same manner as in Example 1, except that the alumina sol provided thereon was changed to AS-3. The layer thickness was approximately 5 μm for both the upper and lower layers.

Comparative Example 2 According to Example 1, alumina sol AS-3 was coated on a substrate and dried to obtain a recording medium.

The layer thickness was approximately 5 μm.

Comparative Example 3 6 parts of alumina sol AS-2, polyvinyl alcohol P
Solid content 9% consisting of 1171 parts VA (solid content) and water
A coating solution was prepared and coated on a polyethylene terephthalate film (manufactured by Ontaisha, OC type, thickness 100 μm) so that the dry layer thickness was approximately 9 μm as shown in Table 1, and dried to obtain a recording medium.

Table 1 shows the evaluation results of the characteristics and printing characteristics of the recording media obtained in Examples 1 to 3 and Comparative Examples 1 to 3. In Table 1, the pore volume of ±10 mm means the ratio of the volume of pores having a radius within ±10 mm of the average pore radius to the total pore volume.

[Effects of the Invention] Since the recording medium of the present invention is coated with two pseudo-boehmite layers having different pore size distributions, it is possible to achieve both sufficient ink absorbency and transparency (low haze).

Claims (1)

[Claims] 1. On the substrate, the volume of pores having an average pore radius of 30 to 50 Å and a radius within ±10 Å of the average pore radius is concentrated at 45% or more of the total pore volume. A boehmite layer is provided, and on top of that, an average pore radius of 15 to 30
A recording medium provided with a pseudo-boehmite layer in which the volume of pores having a radius of ±10 Å of the average pore is concentrated at 55% or more of the total pore volume.